It is desirable to be able to detect when two images are the same, similar or different. Prior art techniques usually apply complex mathematical formulas and take a great deal of computing resources such as processor time and memory. For example, VIMA Technologies of Santa Barbara, Calif. has a technology for image spam detection, but the feature extraction of VIMA's approach is complex: it refers to the intensity of entire image (2-D edge feature), and it refers to the representation of image gradient orientations (SIFT feature). Further, VIMA's approach to image clustering and distance computation is also complex and time consuming.
It would be desirable to provide a more efficient technique for detecting similar images. Further, it would be desirable to use this technique to detect e-mail scams such as phishing and to detect e-mail image spam.